. . . here's a paragraph worth considering:
The research, from the University of New South Wales, suggests that we process information best in verbal or written form, but not in both simultaneously. As so often, it has taken the best efforts of brainy academics to prove what most of us instinctively knew. Trying to follow what someone is saying while watching the same words on a screen is the equivalent of riding a bicycle along a crowded train. It offers the appearance of making extra progress but is actually rather impractical.